Very poor running, help!

Hi all,

I have a 1999 650S curvy and it has a problem that has slowly got worse and the bike was almost unrideable today. Basically it is cutting out / misfiring and I can't work out if its fuel or electrical and I normally have a good feel for that sort of thing It will do it from cold during warm up in a 30mph area, it does it under acceleration and on a steady throttle opening on the motorway, it has been getting progressively worse and today was an absolute nightmare could it be carb icing, HT lead / coil breaking down, fuel starvation, charging issue, battery on the way out, sidestand switch, regulator / rectifier? I do enjoy riding this bike when it's running well but I have honestly replaced almost every part on this bike since buying it and this might be the final straw

I found that making tiny adjustments to the throttle (rather than giving it a handful) when riding minimized the problem a little but it really is doing my head in.

[Biker Biggles]

You have mentioned a lot of the usual suspects but there are one or two more that come to mind.Have you serviced the choke cables and plungers?Could there be an air leak around the carbs/airbox joint or into one of the breather hoses?Crankcase to airbox breathers?(Two of them)
Water in fuel?There is a drain pipe going from the fuel filler area through the tank, exiting under the rear of the tank.If this has corroded inside the tank it just dumps rain into the fuel.
What do the plugs look like?Lean,rich,wet or just right?Not oily hopefully.

[SV650rules]

On a carbed bike Redex can work wonders, its probably good to put 2 or 3 times the normal dose in to start with as a 'shock-and-awe' hit, shake the tank and run it on tick over for a while to let it works its magic on all those carb floats and jets and other gummed up bits, I swear by it on my previous carbed bikes (the lawnmower starts easily after a winter layover with redex in - no more swearing at it in spring LOL). Still use it in my AL7 - cheapest maintenance you will ever buy.

[R1ffR4ff]

All good info above.
Basically give it a decent service.
Plugs/Plug caps/Gaps and condition.
Airfilter clean/blow-out.
Check for Carb air-leaks.
Pull apart and service all electrical multi-connectors.I use Servisol/Maplin's Switch cleaner and ACF50.

Also I give every 2nd or third tank a of fuel a shot of RedX Petrol fuel treatment(Asda/Wilkos)(As per previous poster).It keeps the carbs and fuel system good and if ,"Winterising" helps prevent the fuel from going stale.

Note:Most Gasoline manufacturers change their blend from Winter to Summer and this can affect badly serviced engines more than well kept ones.

Thanks for all the tips, I'm going to set aside a day this weekend and work through it all methodically. I'll let you know how I get on. Thanks again

[ophic]

My mrs' Honda Shadow was running terribly after not being used for a while. This turned out to be gunked up carbs and the local bike shop ran them through an ultrasonic cleaner. After this it's been fine.

The main cost was their time for removing the carbs. If you could get the carbs out yourself, I'd imagine it'd be quite cheap. In fact, you can buy the ultrasonic cleaners for not all that much.

[SV650rules]

Originally Posted by ophic

My mrs' Honda Shadow was running terribly after not being used for a while. This turned out to be gunked up carbs and the local bike shop ran them through an ultrasonic cleaner. After this it's been fine.

The main cost was their time for removing the carbs. If you could get the carbs out yourself, I'd imagine it'd be quite cheap. In fact, you can buy the ultrasonic cleaners for not all that much.

I would try Redex before going to the trouble of removing carbs, after all the redex will get into all the places that the petrol gets, and that is where the gum forms from the dinosaur juice when it evaporates. For less than a tenner its got to be worth a try.

Hi all, after a busy couple of weeks I managed to spend some time in the garage at the weekend:

Battery voltage: 12.6v
Charging voltage: 14.5v
Spark plugs seem to be the same colour (the rear plug was slightly more oily but not much)



I had a look at the carbs as carb icing had been mentioned but haven't had experience of carb heaters before, I'm guessing this is them?



I checked for a voltage but none was present on either carb (with the ignition on but not with the engine running)

I'm not sure what this is but it had a voltage of 5v present:



Another mystery to me:



Possibly a temperature sensor / thermistor? I couldn't get a resistance reading from it though?

I went through every connector I could find and none looked corroded but I gave them a squirt of contact cleaner and WD40 just in case. I made sure the airbox was fitted correctly on the inlet rubbers and it was well sealed. I did find a ropey solder joint with corroded wires where a replacement regulator / rectifier has been fitted at some point so I replaced it. Took the bike for a ride afterwards and although it behaved for a few miles it started playing up again once I got on the motorway, grrrr! I took it for a thrash around our local roundabout GP circuit and as long as it under hard power it seemed to behave but I can't ride like that everywhere! I am now wondering if it is just one cylinder dropping in and out as it sounds a bit off kilter at tickover so I've ordered some Redex to give that a go. After that I'm thinking of replacing the HT leads / plug caps, is it easy to remove the HT leads from the coils or are they bonded in place? Any ideas / suggestions welcomed!

[daktulos]

The black blob on the yellow wires is the thermoswitch. I can't remember what temperature it's supposed to turn the heaters on, but I doubt it's going to be your problem.

[embee]

As all the above suggestions.


I had an odd problem end of last year, it was for all the world like a blocked idle jet which occurred suddenly (shortly after refuelling) Cut a long story short, after a lot of cleaning carbs etc it turned out to be a plug gone down, the refuelling was pure coincidence. New plugs and it ran perfectly, so in case you haven't changed them (even though they look OK) it's a cheap tryout.